Inlet plate for a coating head

ABSTRACT

In a laminated coating head in which drops of coating material are ejected from relatively small orifices in an orifice plate to provide a patterned coating, as in printing, and a filter plate is positioned upstream of the orifice plate to remove any foreign particles from the coating material and prevent clogging of the orifices, an inlet plate having an elongated slot therein is positioned between the filter plate and the orifice plate to thereby form a chamber between the two and allow turbulence generated in the coating by its passage through the filter plate to decay before the coating material reaches the orifice plate. Additionally, the inlet plate is provided with a series of passages extending from the slot and concentrically arranged with respect to the orifices to channelize the flow and eliminate cross flow before the coating material is delivered to the orifices.

iiited States Patent [151 3,645,448 Houser Feb. 29, 1972 {54] INLET PLATE FOR A COATlNG HEAD 72] Inventor: Philip H. Houser, Chillicothe, Ohio [57] ABSTRACT [73] Asslgnec: The Mead Corporation Dayton Ohio In a laminated coating head in which drops of coating material [22] Filed: Nov. 17, 1969 are ejected from relatively small orifices in an orifice plate to provide a patterned coating, as in printing, and a filter plate is [21] Appl" 877,256 positioned upstream of the orifice plate to remove any foreign particles from the coating material and prevent clogging of the 52 us. Cl ..239/15, 346/75 orifices inlet Plate having an elongated herein is P 51 rm. Cl ..B05b 5/00, F23d 1 H28 time! between filter Plate and Orifice P hereby 58 Field of Search ..239/4 3 15- 346/75 Mm a chambe between and "bulence generated in the coating by its passage through the filter plate 5 f to decay before the coating material reaches the orifice plate. 6] Re erences Cl ed Additionally, the inlet plate is provided with a series of UNITED STATES PATENTS passages extending from the slot and concentrically arranged with respect to the orifices to channelize the flow and 3,21 1,088 10/1965 Naiman .239/4 X eliminate cross flow before the coating material is delivered to 3,373,437 3/1968 Sweet et al. ..239/4 X the orifices Primary ExaminerLloyd L. King AttorneyMarechal, Biebel, French & Bugg 5 Claims, 2 Drawing Figures Patented Feb.- 29, 1972 lilnl INVENTOR PHILIP H. HOUSER BY W W,M+@

A TTORNE'YS INLET PLATE FOR A COATING HEAD CROSS-REFERENCE TO RELATED APPLICATIONS Image Construction System Using Multiple Arrays Of Drop Generators, Ser. No. 768,790, filed Oct. 18, 1968; Filter Plate For Coating Assembly, Ser. No. 877,251, filed Nov. 17, 1969 and Method Of Assembling A Coating Head And Subassembly Thereof, Ser. No. 877,255, filed Nov. 17, 1969; the latter two applications filed on even date herewith.

BACKGROUND OF THE INVENTION The above noted related application Ser. No. 768,790 discloses a noncontacting coating system in which a plurality of drops are ejected from a series of small orifices toward a moving web or other article to be provided with a patterned coating, as in printing, with selective drops being charged as they issue from the orifices so that when they subsequently pass through an electrostatic deflecting field established downstream of the charging means they will be deflected from their normal trajectory. A catcher positioned below the deflecting field then catches drops following one path while drops following another path are printed on the web or other article being coated in the desired pattern of coating.

To prevent clogging of the orifices through which the drops of coating material are ejected, a filter plate is positioned up stream of the orifice plate and as closely thereto as practical to reduce the sources of possible contamination to the coating material. While it would be desirable to position the filter plate contiguously to the orifice plate, turbulence generated in the coating material as it passes through the filter plate could The inlet plate is mounted beneath the filter plate 20 and has a slot 31 formed therein extending longitudinally in a position such that it is substantially aligned with the perforated central portion 23 of the filter plate 20. Extending downwardly from the bottom of the slot 31 are a series of passages 32 and adjacent one end of the inlet plate 30 and in communication with the slot 31, is a cleanout port 33 which is normally closed by cover plate 34 attached to the inlet plate 30 by means of bolts or the like.

An orifice plate 40 having a series of orifices 41 through which the coating is ejected is positioned beneath the inlet plate with the orifices 41 concentrically positioned with respect to the passages 32 in the inlet plate. The orifice plate is spaced from the next component of the coating head by means of a spacer plate 50 positioned between the orifice plate and a charge ring plate 51.

The charge ring plate 51 has a series of charge rings 52 connected through leads 53 and connectors 54 to a source of power 55, whereby an electric charge may be imparted to drops of coating material as they are ejected from the orifices 41. The charge ring plate and its associated charge rings and deleteriously affect the coating operation by causing nonuniformities in the drops of material being ejected throughthe orifices.

Additionally, since only a small number of perforations through the filter plate would be in communication with the orifices if The orifice plate and the filter plate were in contacting relationship, clogging of a small number of perforations through the filter plate during the filtering operation, would, in effect, block the orifice immediately opposite such perforatrons.

SUMMARY OF THE INVENTION An inlet plate member is positioned between the filter plate and the orifice plate to provide a chamber in which turbulence generated by the passage of the coating material through the filter plate is allowed time to decay before the coating material reaches the orifices. The inlet plate further serves to present a greater number of perforations in the filter plate to each of the orifices since, in effect, all of the perforations are in communication with all of the orifices Thus, should several of the perforations become blocked the total How to the orifices will not be appreciably affected. Additionally, a series of short passages are provided extending from the bottom of the slot in the inlet plate in concentricity with the orifices in the orifice plate. Therefore, any crossflows generated upstream of the orifice plate are dampened and the coating flow substantially channelized in a direction parallel to the axes of the orifices.

BRIEF DESCRIPTION OF THE DRAWING FIG. I is an exploded perspective view showing, somewhat schematically, the various components of a laminated coating head; and

FIG. 2 is a perspective view of a portion of an inlet plate.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As seen in FIG. I of the drawings, a typical laminated coating head may comprise a manifold 10 having a chamber 11 opening outwardly, as at 12, and a conduit 13 for delivering coating material to the chamber 11. A filter plate 20, interposed between gaskets 21 and 22, is positioned immediately beneath the manifold 10 with its perforated central portion 23 positioned in opposition to the opening 12.

leads may conveniently be constructed by conventional printed circuit techniques although it will be appreciated that the degree of precision required will be somewhat greater than that necessary for conventional printed circuitry. The clamp plate 56 is positioned adjacent the charge ring plate 51 and a series of bolts (not shown) pass downwardly through all of the components of the laminated coating head and are threadedly received in a clamp plate to secure the components together in laminar relationship.

A pair of electrodes 57 are positioned downstream of the charge ring plate and all drops of coating material, whether charged or uncharged, pass through the electrostatic field set up by the electrodes 57 and are accordingly, deflected or not deflected depending upon whether or not they have received a charge as they pass through the charge ring plate. A catcher 58 then catches those drops of coating material which it is desired to prevent from being deposited on the article being coated, all as described in the above noted related application Ser. No- 768,790.

While on the one hand it is desirable to place the filter plate as closely as possible to the orifice plate, as a practical matter it is necessary to provide some space between these two components. Thus, should several of the openings in the filter plate become clogged, by providing a reservoir immediately upstream of the orifice plate, as by means of the slot 31, it is only necessary for the coating to flow at a higher velocity through the unclogged perforations in the filter plate to keep the reservoir formed by the slot 31 filled and present a constant supply of coating material to the orifices 41.

Additionally, the passage of the coating material through the perforations in the filter plate may generate some turbulence. By providing a chamber between the perforations and the orifices in the orifice plate the turbulence generated is allowed time to decay before reaching the orifices 41. It will also be seen that crossflows or the like generated upstream of the orifices 41 are channelized during the passage of the coating through the passages 32 immediately upstream of the orifice and hence, an essentially unidirectional flow is presented to each of the orifices 41.

From the above it will be apparent that the present invention provides means for permitting a filter plate to be used in conjunction with an orifice plate in noncontacting printing apparatus while at the same time eliminating the disadvantages of placing a filter plate of this type immediately upstream of the orifice plate.

While the form of apparatus herein described constitutes a preferred embodiment of the invention, it is to be understood that the invention is not limited to this precise form of apparatus, and that changes may be made therein without departing from the scope of the invention.

What is claimed is:

l. in a noncontacting coating head including a coating material manifold, a filter plate having a plurality of perforations formed therein, an orifice plate positioned downstream of said filter plate and having a series of orifices formed therein, a series of charge rings for selectively charging coating material ejected through said orifices, means for establishing an electrostatic-deflecting field downstream of said charge rings and means for selectively catching drops of coating material. the improvement comprising:

a. an inlet plate member positioned between said filter plate and said orifice plate,

b. said inlet plate having an elongated slot therein extending from the surface of said inlet plate adjacent said filter plate toward said orifice plate.

2. The improvement of claim 1 further comprising:

a. a series of passages formed in said inlet plate member and extending from said slot to said orifice plate,

b. said passages being concentric with said orifices in said orifice plate.

3. The improvement ofclaim 2 wherein:

a. the axes of said passages are substantially parallel.

4. The improvement ofclaim 3 wherein:

a. the depth of said slot is appreciably greater than the length of said passages.

5. The improvement of claim 4 wherein:

a. a said inlet plate is approximately 0.1875 inch thick,

b. said slot is approximately 0.1875 inch deep, and

c. said passages are approximately 0.0635 inch in diameter.

T222? UNITED 4.113s PAHEJHI 0mm; I CERTIFICATE OF CORREC'EIGN Patent No- 3,645,448 Dated February QQ 107? Inventor(s) Philip H. Houser It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:-

Column 4, line 12, "a. a said" should bea. said-.

Column 4, line 12, "0.1875" should be0.250--.

Signed and sealed this 5th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents Patent No- 3,645,448 Dated February 79 1 Q77 Inventor(s) Philip H. Houser It is certified that error appears in the aboveidentified patent and that said Letters Patent are hereby corrected as shown below:-

Column 4, line 12, "a. a said" should be-a. said--.

Column 4, line 12, "0.1875" should be-0.250-.

Signed and sealed this 5th day of September 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner of Patents 

1. In a noncontacting coating head including a coating material manifold, a filter plate having a plurality of perforations formed therein, an orifice plate positioned downstream of said filter plate and having a series of orifices formed therein, a series of charge rings for selectively charging coating material ejected through said orifices, means for establishing an electrostatic-deflecting field downstream of said charge rings and means for selectively catching drops of coating material, the improvement comprising: a. an inlet plate member positioned between said filter plate and said orifice plate, b. said inlet plate having an elongated slot therein extending from the surface of said inlet plate adjacent said filter plate toward said orifice plate.
 2. The improvement of claim 1 further comprising: a. a series of passages formed in said inlet plate member and extending from said slot to said orifice plate, b. said passages being concentric with said orifices in said orifice plate.
 3. The improvement of claim 2 wherein: a. the axes of said passages are substantially parallel.
 4. The improvement of claim 3 wherein: a. the depth of said slot is appreciably greater than the length of said passages.
 5. The improvement of claim 4 wherein: a. a said inlet plate is approximately 0.1875 inch thick, b. said slot is approximately 0.1875 inch deep, and c. said passages are approximately 0.0635 inch in diameter. 